DE69635423T2 - THERMAL SURGERY SYSTEM WITH COLD ELECTRIC TIP - Google Patents

Abstract

For heat ablating living tissue of a body, an ablation electrode (11, 192), contacting a surface of the tissue or within tissue, is coupled to an RF power supply (16, 136, 166, 262) referenced to a second electrode contacting the body. Fluid coolant is circulated to cool the contact surface extending the ablation to an increased volume of tissue. Temperature may be sensed contiguous to the surface to control the flows of RF heating energy and fluid coolant. Computer capability implements control and provides graphics displays of data, preplans, or controls relative to the ablation. Several forms of electrode structures accommodate specific objectives. <IMAGE>

Description

background and Summary of the Invention

therapeutic lesions in living bodies have been using radio frequency (RF) for many decades and other forms of energy. The interventions are special useful in the field of neurosurgery, especially when RF ablation electrodes (usually in oblong cylindrical Form) into a living body introduced become. A typical form of such ablation electrodes contains an insulated sheath from which an exposed (non-insulated) Tip stretches.

in the Generally, the ablation electrode becomes between a grounded RF power source (outside of the body) and a reference ground or a neutral electrode and for contact with a large surface of the body designed. When an RF voltage between the reference electrode and the introduced Ablation electrode is generated, RF current flows from the ablation electrode through the body. Normally, the current density is near the tip of the ablation electrode very high, which heats and destroys the adjacent tissue.

Ablation method including the underlying theory of the method and many applications for the Methods are described in various publications, and in particular in 1. Cosman et al., Theoretical Aspects of Radiofrequency Lesions in the Dorsal Root Entry Zone "Neurosurg 15: 945-950, 1984, and 2. Cosman E.R. and Cosman B.J .: Methods of Making Nervous System Lesions, in Wilkins RH, Rengachary SS (EDS): Neurosurgery, New York, McGraw-Hill, Vol, III, Pp. 2490-2498, 1984th

In In the past, RF ablation electrodes are temperature sensors integrated, for example in the form of a thermistor or Thermocouple. In this regard, reference is made to U.S. Patent No. 4,411,266 (1983, Eric R. Cosman). Usually the sensor with a monitoring device which indicates the temperature which is the generation of a desired lesion allows. As is well known, can with a certain shape of the tip and temperature of the tip lesions with a prescribed size right reliable getting produced. Also in this regard is US Patent 4,411,266 (1983, Eric R. Cosman).

in the Over the years, there is a wide range of shapes and configurations used by HF electrodes Several recent forms of Radionics, Inc. (Burlington, Massachusetts) can be obtained. These electrodes have been used to treat lesions in a wide range of goals in the body including of the brain, the spine and the heart.

A restriction however, prior art electrode ablation systems are concerned with Temperature of the tip. This means, previous ablation electrodes with a certain tip shape should effectively never exceed a temperature of 100 ° C. At this temperature it comes to the fact that the fabric boils and charred. Furthermore can cause uncontrolled destruction, such as bleeding or formation of explosive gases, extraordinary threatening and clinically dangerous Have an impact on the patient. Therefore, the size of the lesion is for a specific one Electrode shape in general than by the fact that the tissue near the top is 100 ° C do not exceed may, as to some extent limited been considered.

Fundamental For RF ablation, the electrode temperature is near the tip the highest, because the current density is highest at this point. Accordingly it falls Temperature in dependence from the distance to the electrode tip, and that, apart from possible abnormalities in terms of conductivity tissue, etc., in a predictable and even predictable way. This As a result, the size of HF lesions for a given Electrode shape restricted has been.

A suggested solution in terms of restriction the size of lesions in use of "off-axis Off-axis electrodes, for example, the so-called cervical hypophysectomy-Electrode or the Gildenberg Side-Outlet Electrode, as manufactured by Radionics, Inc., (Burlington, Massachusetts). In such systems, the However, this will increase the number of tissue functions required Risk of bleeding, the time of the surgical procedure is considerably prolonged, and the degree of sensitivity increases. Also a group of Dislocated lesions may result not a desired homogeneous or uniform lesion. Therefore, there is a need for an ablation electrode system, with the enlarged lesions (radius and volume) can be made.

With regard to the size of the lesion, the publications by Cosman et al. (mentioned above) making lesions in the brain of 10 to 12 millimeters using very large electrodes. However, there is a need to make significantly larger lesions. For example, in the liver carcinogenic tumors can be larger than 20 or 30 millimeters and clearly visible, such as tomographic Ab shift keying. Accordingly, there is a need to destructively heat such tumors with a minimum number of electrode insertions and heats.

The European Patent Application 0 310 431 to Cavitron, Inc. relates to methods and devices for producing improved tissue fragmentation and / or hemostasis. The device contains a tip that can be vibrated to tissue to decompose a surgical procedure with ultrasound and that decomposed tissue and fluid through an opening in the tip of the surgical site to suck. A connection with the electrosurgical unit allows the supply of RF cutting current, HF clotting current or a combination thereof to the tip, so that electrosurgical intervention separately or simultaneously be performed with ultrasonic suction through the top can.

The International Application PCT / US94 / 06124 (International Publication no. Irman, WO 94/28809 relates to a transurethral radiofrequency ablation device which a probe that is a flexible oblong tubular element with proximal and distal ends, and a cylinder liner ablation electrode comprises, which consists of a conductive material and of the distal End of the flexible elongated tubular element is worn and has a bore therein. The flexible elongated tubular element is with a first flow lumen for supplying a cooled Fluids to the bore of the ablation electrode and a second Flow lumen to return of the chilled Fluid provided. The probe is connected to facilities that add a coolant solution to the probe to supply the radio frequency energy to the electrode and at the same time cool, and monitor the temperature of the ablation electrode so that the ablation electrode kept at a temperature below a predetermined temperature becomes.

US Patent Cosas 4,565,200 relates to a universal lesion and recording electrode system, that one cannula with a passage opening over her Length, the passage opening at the distal end of the cannula directed forward, a straight lesion electrode telescoping so in the cannula sits that the exposed metal tip of the electrode around a changeable one Measure over the distal tip of the cannula can extend out, and one with an off-axis tip contains provided electrode, which also sits telescopically in the cannula, so that their not isolated tip from the distal end of the cannula in an off-axis Exit direction.

US Patent 5,267,994 to Gentelia et al. concerns an electrosurgical Probe containing an electrosurgical tip, a cylindrical Body, which is attached to the top, and contains a pedestal, the on the cylindrical body is appropriate. The cylindrical body is substantially hollow, so that sucking, rinsing and laparoscopy or laser surgery can be performed via the probe. Of the cylindrical body consists of an insulating material to prevent accidental electric shock for the Avoid patients. A device for conducting electrical Current to the electrosurgical tip from the distal end of the probe also available.

in the In general, the system of the present invention relates to an improved one System for performing of ablation procedures in the body. The System offers the possibility Controlled and modified temperature distribution as a function of Distance to the ablation electrode to "expel" or distribute the heat over much greater distances, while at the same time in general safety and control the lesion process be maintained.

Accordingly The present invention provides an electrical structure for Target detection and ablation of a given tissue volume to the formation of a lesion to maximize as defined in claim 1. preferred versions The present invention is set forth in dependent claims 2-12.

The electrical structure enables control of the temperature at a heating termination, such as the tip of an ablation electrode. For example, in disclosed embodiments, the temperature of the electrode tip (heater) is controlled by incorporating a mechanism that cools the tip so as to reduce the excessive temperatures during the ablation process to the tip. Thus, the use of a controllable externally modulated drug (fluid) to secondaryly cool the tip will provide control and thereby reduce excessive heating of tissue near or adjacent the tip. In particular, disclosed embodiments include a cooling member that allows cooling of the ablation electrode and tissue immediately adjacent to the electrode so as to modify the thermal distribution of the heat conditions in the tissue and produce larger lesions. In essence, the ablation energy that is dissipated in the tissue as heat can be effectively increased by cooling on the processing surface. This increases the ablation volume. Cool tip forms of high frequency electrodes as disclosed herein are well suited for minimally invasive ablation of tumors. Special designs are useful disclosed for thermosurgical use, wherein they have physical properties that allow improved control and handling. Specific arrangements of cannula, fluid transport structures, irrigation and perfusion devices, radiofrequency cannulas, and thermoprobes are disclosed which provide the ability to construct various practical thermosurgical applicators that function effectively. Furthermore, as is apparent here, control may be enhanced by the use of a computer, such as graphics and display capability to control, monitor, or feedback parameters of the thermosurgery, and to plan ablation in advance, or images of one or more of them to image, merge or update multiple image scanners before, during or after the ablation process.

Short description the drawings

In the drawings which form a part of the specification are exemplary embodiments, which have various tasks and characteristics, listed, i.

1 Fig. 12 is a block diagram and sectional diagram of a system constructed in accordance with the present invention;

2 FIG. 4 is an enlarged partial block diagram and section showing portions of the system in FIG 1 in larger structural detail with minor modifications.

2A Figure 5 is a section and a view of separate components representative of an alternative embodiment according to the present invention;

2 B is a partial view showing another alternative embodiment to that in FIG 2A shows;

2C is a partial view showing another alternative embodiment to that in FIG 2A shows;

2D FIG. 12 is a sectional and a view of disassembled components of another alternative form of the electrode component of the system in FIG 2 ;

3 FIG. 4 is a rectangular coordinate diagram illustrating temperature distributions associated with RF electrodes; FIG.

4 Figure 4 is a block diagram and schematic diagram of an alternative form of system according to the present invention;

5 Figure 4 is a block diagram and a view of another alternative form of the present invention;

6 Figure 4 is a block diagram and a view of another alternative form of the present invention;

7 is a schematic representation of a system according to the same in a further modified form;

8th Figure 4 is a block diagram and schematic view of an extended embodiment of the system of the present invention;

9 is a computer program flowchart illustrating operations in the system 8th represents;

10 is a pictorial view of exemplary displays of the system in FIG 8th ; and

11 FIG. 10 is a sectional view illustrating an exemplary engagement using one form of the system of the present invention. FIG.

Description of the invention

The following versions illustrate the present invention and principles thereof by way of example However, they are considered to be the best available for disclosure purposes and as Basis for the following claims which define the scope of the present invention.

Like at the same time in 1 and 2 Generally, the illustrated ablation system generally includes an elongated shaft or cannula body C for percutaneous or intraoperative insertion into an open wound site. As shown, the cannula body is integrally formed with a hub member H which is coupled to remote auxiliary components collectively designated S.

The cannula body 10 structurally contains an elongated hollow ablation electrode 11 ( 2 ), which consists of conductive material, such as metal, such as stainless steel, titanium, etc. At the distal end of the cannula body 10 points the electrode 11 a peak 12 which may be rounded or pointed at its end. In a mold, the tip can 12 have a trocar tip and be a robust metal construction to allow insertion or penetration into tissue. In function, it spreads when an RF energy source 16 is inserted, electric current from the top 12 and passes through the surrounding tissue so that the tissue heats up. That is, when the top 12 Being located adjacent to (near, touching or within) tissue becomes energy from the RF energy source 16 released into heat in the tissue.

The electrode carries most of its length 11 an insulating coating 13 , which selectively allows the flow of electrical current from the shaft 15 the electrode 11 prevented in surrounding tissue. So shields the insulating coating 13 the intervening tissue from RF current to allow this tissue over the length of the shaft 15 essentially to the heating effect of the exposed tip 12 not heated.

The proximal (left) end of the electrode 11 ( 2 ) is integral with an enlarged housing ( 14 ) in the hub H, which receives electrical and refrigerant connections, as will be explained in detail below. Outside the patient's body is the case 14 cylindrically shaped and has connections for connection to the auxiliary components S, ie the electrical and Flurdverbindungen. The housing 14 may, as indicated, integral with the electrode 11 be connected and made of metal, or may, as described below, form a separate sub-assembly. Alternatively, the housing may 14 Made of plastic and record separate electrical connections. In this case, a plastic housing is suitable 14 for x-ray imaging, CT, MR, etc. with low artifacts, as may be advantageous in some situations.

The housing 14 is with a block eighteen ( 2 ), which has a luer connection 19 has, with which the block eighteen sealed to the housing 14 is appropriate. So fluid and power connections are available. That is, connection to a regulated RF source 16 (Variable) may be in the form of a standard cable connector, a lead wire, a receptacle contact, or other constructions known in the art of radio frequency engineering. The electrical temperature sensing and high frequency connections can be made through the housing 14 be made and get to the area of the top 12 extend where an RF line 25 with connection 21 (a welding, soldering or other secure electrical connection) is connected. If there are sensor cables 24 to a thenmosensor 23 , for example, in the form of a thermistor or a thermocouple, or another type of sensor, the sensor may 23 with the wall of the top 12 welded or brought into thermal contact with the temperature of the tip 12 capture.

The RF energy source 16 can, as already stated, be related to a reference potential, as shown ( 2 ), and over the block eighteen , which is attached to the hub H, to be connected. That is, the RF energy source 16 leads to the connection port 21 RF voltage across the block eighteen with an electrical connection to the electrode 11 to, as with the line 25 is indicated. The energy source 16 may be in the form of an RF generator, such as the RFG-3C HF Lesion Generator system, available from Radionics, Inc. (Burlington, Massachusetts).

When the ablation electrode 11 is located in the body of a patient, as indicated above and common practice, an electrical circuit through the body to a reference or dispersion electrode R (in 2 symbolically represented) closed, which is connected elsewhere with the body. This heats the RF energy source 16 Body tissue by current of the tip 12 , In this case, a temperature monitoring device 20 ( 2 left center) through lines 22 and 24 with a temperature sensor 23 , for example in the form of a thermocouple or a thermistor, which are normally in the tip 12 is or is in contact with her. The sensor 23 is, as shown, with the top 12 connected. The sensed temperature may be used to control either the flow of RF energy or the flow of coolant, or both, to achieve the desired ablation while maintaining the maximum temperature substantially below 100 ° C. It should be noted that a variety of sensors could be used, including units extending from the tip 12 extend out to measure temperatures at different positions near the top 12 to rule. At the temperature monitoring device 20 For example, these may be the TC thermocouple temperature monitoring devices available from Radionics, Inc. (Burlington, Massachusetts).

Accordingly, temperatures can be at the top 12 or in their vicinity (through the monitoring device 20 embodied) by controlling the flow of liquid coolant through the ablation electrode 11 is controlled. Accordingly, the temperature of the tissue is near or in contact with the tip 12 controlled. In the disclosed embodiment, fluid is delivered from a fluid source FS over the length of the ablation electrode 11 ( 2 ) through a tube 26 directed, extending from the housing H to the distal end of the electrode 11 extends and at an open end 28 at the top 12 ends. At the opposite end of the electrode 11 in the housing H is the tube 26 connected so that it absorbs fluid. Like in the detailed structure in 1 As shown, the fluid source FS includes a source unit 34 that have a control 32 is connected, for which a syringe 30 is used to fluid flow (arrow 38 ) via a coupling 38 trigger. Thus, fluid flow is regulated according to the observed temperature, allowing for increased flow of RF energy.

The liquid coolant may be in the form of water or saline to heat by convection from the top 12 derive. The container or source unit 34 ( 1 ) may be a large container of chilled water, physiological saline, or other fluid. As a simplifying example, a container of water with ice cubes may serve to maintain the coolant at a temperature of near 0 ° C. As another example, the fluid source FS could include a peristaltic pump or other fluid pump or could be merely gravity fed to introduce fluid from a bag or rigid container.

Current away from the top leads back to the hub H ( 2 ) and exits the hub H via an exit port 14 out, like this by arrows 42 and 43 is shown. It should be noted that the ports may be in the form of simple clutches, rigid units, or may include flexible tubular couplings to transmit torque to the electrode 11 to reduce. Furthermore, the coolant flow elements may simply be in the form of PVC tubes with plastic Luer connectors to facilitate use.

Due to the flow of coolant, the interior of the electrode 11 , in particular the electrode tip 12 , are kept at a temperature close to that of the fluid source FS. The coolant can, as in 2 shown to circulate in a closed system. In some cases, it may also be advantageous to reverse the direction of the fluid flow from that shown in the figures. Coordinated function, which includes RF heating along with cooling, may be accomplished with a microprocessor, as discussed in detail below 44 ( 2 ) can be achieved. This is the microprocessor 44 with the RF power source 16 the temperature monitoring device 20 and the fluid source FS connected to receive data on flow rates and temperatures and to perform control. Accordingly, an integrated function with feedback from the temperature monitor becomes 20 achieved in a controlled manner, and various functions can be performed simultaneously. Thus, facilitated by the cooling, the ablation electrode 11 moderated, altered, controlled or stabilized. Such controlled operation can lower the temperature of tissue near the tip 12 effectively to achieve a uniform temperature distribution tailored to the desired size of the desired lesion.

The temperature distribution in the tissue near the tip 12 depends on the HF current from the top 12 and depends on the temperature of the tissue that is at the top 12 adjacent, and this peak temperature can be controlled so that it approaches the temperature of the fluid from the source FS. Thus, a thermal boundary condition is established, so that the temperature of the tissue (near the top 12 ) is maintained approximately at the temperature of the tip itself, z. B. the temperature of the fluid inside the tip 12 , Accordingly, by controlling the temperature, the surgeon can set a predetermined temperature at the boundary of the electrode tip 12 which, in a sense, may be independent of the RF heating process and significantly modify the temperature distribution in the tissue.

To temperature distributions from the top 12 The following is the diagram in 3 Referenced. The radial actual distance R to the central axis of an electrode tip is shown as a function of the temperature T. In the illustrated example, an actual radius R _{0 of} the peak is shown. A body temperature of 37 ° C is the basic reference line in the diagram. Furthermore, a temperature level of 100 ° C is shown, ie the boiling point of water and essentially that of body tissues. Such a temperature is, as explained above, extremely disadvantageous in any controlled clinical environment. Accordingly, it is important to keep the temperature of the electrode substantially below 100 ° C.

In general, the curves in 3 in some sense, ideal characteristics of exemplary electrodes showing the tissue temperature T as a function of the distance R to the electrode. The curves, though idealized, are predictable and may serve to indicate the size of the lesion. In this regard, reference is made to the above-cited publications by Cosman et al. (both 1984).

The curve 51 represents the function of a conventional ablation electrode, in which at the electrode surface (R ₀ ) the tissue is raised to a safe temperature T ₁ . From this point, however, the temperature drops rapidly and, as the distance R to the electrode decreases, reaches asymptotic body temperature (37 ° C).

It is generally accepted that most Body tissues permanently die over most cell lines if they are maintained at a temperature in the range of 45 ° C to 60 ° C for an extended period of time, for example 60 s. Accordingly, the lesion radius for a lesion generally corresponds to the radius associated with temperatures in the range of 45 ° C to 60 ° C. So would be ablation through the electrode, as with the curve 51 is shown, only in the radius of a point 53 effective.

The curve 52 FIG. 10 illustrates the characteristic of an electrode or ablation system according to the present invention. The improved electrode (eg, electrode 11 . 2 ) may be maintained at an approximate temperature, such as indicated temperature T ₀ , which is substantially lower than the body temperature of 37 ° C. In 3 is shown that the temperature T ₀ 0 ° C, ie the freezing point of water, can approach. Of course, it is not necessary to use such a low temperature, the diagram in 3 However, it is also for illustrative purposes only. Therefore, a substantially horizontal section shows 54 the curve 52 a constant temperature T ₀ within the radius R ₀ . The section 54 illustrates a situation in which the interior of the improved electrode tip is maintained at a temperature T ₀ by circulation of coolant. Such an operation he testifies the boundary condition at R ₀ , so that the tissue outside the top also has substantially the temperature T ₀ .

From further illustrations of the curve 52 shows that the HF flow adjacent and causes power dissipation in the tissue directly at the electrode radius R ₀ at a distance therefrom, the equilibrium temperature distribution of the fabric but is controlled by balancing the distribution of heat conduction and convection through the entire room. The fact that the improved electrode tip (tip 12 . 2 ) is kept at the temperature T ₀ , means that the temperature curve 52 must be continuous and hits the point T _o at radius R _o . As a result, the heating causes higher temperatures at greater distances to the tip, as with the rise of the curve 52 is shown at a maximum temperature T ₁ at a radius R ₁ , which is considerably larger than the radius R ₀ . The actual ablation radius is at one point 57 shown opposite the point 53 has shifted considerably.

Beyond the radius R ₁ , there is blood convection in a larger radius, and the curve 52 As shown, it drops to its asymptotic limit, which approaches 37 ° C.

The curve 52 illustrates that, by cooling in the improved electrode tip, the radius R ₁ corresponding to a temperature T ₁ is significantly greater than the radius corresponding to the same temperature T ₁ for traditional electrodes. That is, by cooling the electrode tip, the zone of highest temperature is "expelled" or expanded to a larger radius, in the illustrated case to a radius R ₁ farther from the electrode than the radius R _{o of} conventional electrodes also applies to the ablation radii, as with the points 53 and 57 is shown.

In summary, the consequence of the larger radius of higher temperature is a larger kill radius. That is, the killing radius or the volume of the ablation zone can be significantly increased in a cooled electrode having substantially the same shape. This can be done with the radius for the point 57 on the bend 52 compared to the point 53 on the bend 51 be illustrated. Thus, a quantum leap is the ability to create RF lesions and produce larger lesions with better control in a particular electrode shape. Reactions according to the disclosed real living tissue embodiments show that for an electrode having a thickness of 20 gauge (in Radius of less than 1 mm) lesion sizes can be extended from a restricted range of about 10 mm diameter to 20-30 mm diameter. The consequences are significant.

At the Clinical use, the systems have a significant material Advantage on. So can for one Tumor volume in the range of 20 mm or more a single electrode be used to adjust the volume in a lethal temperature zone include. In contrast, would be at conventional Electrodes several passes or several off-axis passes with electrodes with all of them associated disadvantages and dangers of bleeding, malaise, the danger of meeting sensitive structures, inequalities of temperature distribution and the danger, not the whole concerned Volume removal required. So are accordingly at Ablation of tissue volume has achieved significant clinical benefits.

From the above description, it will be apparent to those skilled in the art that the present invention may be embodied in a number of different forms. The execution in 1 and 2 be implemented in various ways, such as disposable or usable several times. The heat circulation system may be an intact tissue-penetrating closed-end structure. Temperature sensors and monitoring devices may or may not be used in the electrode or applicator Not.

Because the temperature sensor 24 its failure does not affect the specific function of the cannula body C. In general, the modularization may include separate units including the heating, cooling and sensing operations to allow for separate and separate reusability or disposability.

Various forms of plastics, metals and composites can be used to accomplish specific tasks. The insulating coating 13 For example, it may be in the form of Teflon, polyethylene, etc. as was the case with previous electrode designs available from Radionics (Burlington, Massachusetts).

In the following special alternative forms are described and 2A FIG. 12 illustrates a two-component structure. Shown at the top is a cannula casing CS which telescopically receives an occluding stylet stem SS, the two meshing, for example, with body tissue. Subsequently, upon engagement, the stylet shaft SS is removed from the cannula jacket CS, and a cooled RF cannula RC is separately inserted as shown. This achieves a slightly greater flexibility of the function.

The cannula shaft CS may have an elongated tubular insulated structure (for example in the form of a plastic sheath or an insulation covering a metal tube). 182 be that at a hub 184 is attached. In general, the isolated structure 182 an electrically insulating substance as a surface on while the hub 184 may be made of either metal or plastic, the latter possibly being a low radiopacity material which is advantageous for X-ray, CT, MRI, etc. positioning.

The guide shaft SS is loose in the isolated structure 182 received for unobstructed telescopic movement and can be a tapered front end 186 which may be a trocar, conical, bevelled or other penetrating form for introducing said combination into the body of the patient. When inserting is the hub 184 with the block 188 engaged to lock and seal the cannula sheath CS with the guide shaft SS and achieve effective insertion.

When the combination or cannula sheath CS and the guide rod shaft SS are suitably arranged in the composite in the composite, the guide rod shaft SS is withdrawn and the cooled cannula RC is inserted. Accordingly, as by the double arrow 190 indicated, the positions of the guide rod shaft SS and the cooled RF cannula RC opposite to the illustrated. When the cooled cannula RC is received in the cannula sheath CS, a tip extends 192 around the length L from the insulation 182 as indicated. Accordingly, the unit is mobilized for effective heat ablation.

Considering the cooled cannula RC in detail, as already described with reference to the foregoing, both heating and cooling capability are ensured. Not all details of the cooled RF cannula RC are in 2A repeated. Instead, items are generally indicated. That is, from the tip d192, the hollow electrode extends 194 (with substantially uniform cross-section) continue (to the left), with a setting clamp 196 to be engaged, which allows different lengths as in known structures. That is, in a conventional Einstellklemme 196 may be the length L of the protruding tip 192 be varied to meet various desired tasks. The adjustment clamp 196 is with a safety screw 208 attached.

When using the structure in 2A becomes a measure of the effective peak length (degree of projection L) by scale marks ( 198 ) on a cylindrical section 200 (left), which is different from the adjustment clamp 196 extends. Removed from the clamp 196 comes the section 200 with a clutch 202 engaged, in turn, a connector block 204 which receives an electrical connection 194 from the electrode tip 192 or the cannula RC to a source 206 from the RF energy carries, as stated above with reference to 2 is explained.

Coolant passing through the top 192 is about to circulate, is about tubes 210 and 212 provided. So as detailed with reference to 1 and 2 described the tubes 210 and 212 the passage of coolant fluid through the RF / cooling cannula RC to the tip 192 so as to cool or "pinch" the tip to the desired temperature, which may be below 37 ° C. Accordingly, as discussed above, the structure "pushes" the temperature distribution outward to achieve a greater ablation volume ,

2 B is slightly enlarged and shows a variation of 2A , That is, a directional electrode 214 in 2 B has an insulated sheath 216 , the full ring of the casing 216 but ends in a band 218 , From the band 218 an covers the jacket 216 only one half of the electrode tip 220 in the form of a Läng union half shell extension 222 from. Accordingly, an exposed conductive surface of the tip 220 (approximately an arcuate semi-cylindrical surface) at the top of the tip while the other half of the tip is isolated to prevent the leakage of RF current. Therefore, the RF current is directed into the tissue, and thereby the ablation occurs directionally. That is, the fabric is attached to a "window" in the insulation by the exposed (top) side of the tip 220 heated, but not on the opposite, shielded by insulation lower side. When using the execution in 2 B Nonsymmetric lesions are possible. Another modification is with the modified partial view in FIG 2C represented, which in turn represents a modification of the structure, as shown in 2A is shown. The summit 221 has a side cutout 223 who, by reference to 2 B described with the tip end covered or partially covered. The modification may be used as a biopsy needle, a suction device, a suction tube device, a side-scanning subsonic detector, or a radar system, for example, when biopsies, aspirations, etc., over the cutout 223 can be performed. These side-cut or fenestrated biopsy needles are known in the industry, such as the NBA Nashhold biopsy needle manufactured by Radionics, Inc. (Burlington, Massachusetts).

Another modification of the system, as in 1 and 2 is shown in 2D shown. The structure in 2D essentially contains four separate components (shown separately), which are assembled one after the other to perform an ablation. That is, the interconnected components are telescopically engaged as shown by broken lines L1, L2 and L3 to produce an integrated system.

In essence, an isolated cannula IC (top) receives an electrode guide rod ES, which in turn receives a coolant cannula CC, which in turn receives an RF element RE. Although the items are somewhat similar to the parts described above, they also differ as will be described below. Where appropriate, however, like reference numerals are used. An ablation electrode 11 ( 2D top right) that can be connected to an RF source (not shown) has a tapered tip 12 which is distinguished by an insulating coating 13 from which extends the electrode 2 covering from the top of a H1 hub. The summit 12 allows, as already explained, intrusion.

Removed from the top 12 can the hub H1 ( 2D ), like the other hubs in 2D Various materials, including metal or plastic, include and have a male Luer shape 224 (broken line) coaxial with the electrode 11 to receive a male locking. The socket shape 224 the hub H1 takes the plug-in luer shape as shown 226 a hub H2, a part of the electrode-guide rod ES, on.

When the isolated cannula IC is disposed in the tissue, the electrode guide rod ES is telescopically inserted to form an elongated coaxial guide rod 228 essentially over the length of the hollow electrode 11 extends. The lockingly engaged elements provide a somewhat stiffer structure for effective handling and penetration into tissue or for entry into body orifices.

When the combination (the insulated cannula IC and the electrode guide rod ES) has been appropriately engaged and arranged, a coolant cannula CC is inserted into the guide rod ES. The coolant cannula CC includes a hub H3 having a male luer shape 230 to telescope the entire assembly during the period of heat ablation in the guide rod 228 to lock.

Looking in more detail at the structure, it can be seen that the hub H3 has axially parallel channels that allow the flow of coolants. A radial tube 232 enters the hub H3 below to supply a coolant flow passage from the hub H3 to a coolant tube 241 essentially over the length of the management staff 228 extends.

Another fluid channel 234 (top) passing through the hub H3 branches axially from a port 236 to allow the exit flow of coolant, as indicated by the arrow 238 is shown. Accordingly, coolant is passed through a tube 232 picked up, moves over the length of the unit and enters the tube 234 out. As a result, cooling is achieved accordingly.

The hub H3 further has a coaxial Luer opening 240 for engagement with a plug-in Luer shape 242 in a hub H4 of the RF element RE ( 2D below). Accordingly, the element RE can be introduced so that an elongate detecting element 244 coaxial in the elongated tube 246 the coolant cannula CC on is taken. Accordingly, an end 248 of the element RE at the distal tip of the tube 246 arranged. The summit 248 (RF element RE) may include a thermal sensor that senses the temperature of the coolant fluid, or it may be configured to mate with the wall of the tip 12 comes into contact to detect the tissue temperature in the vicinity. The hub H4 has a plug-in luer connection 242 to plug in at the socket luer opening 240 seal. Furthermore, the element RE is via the hub H4 with an external electrical unit 251 over a cable 250 connected, as described in the other embodiments, wherein the unit 251 for example, an electrical power or other energy source for generating heat in the tissue near the tip 12 is.

The system in 2D can be done in a simpler form. For example, for the isolated cannula IC, if it is sufficiently stiff, the stylet rod is 228 not required for penetration. The coolant cannula CC can only have a single channel, such as the tube 241 , for fluid circulation without the tube 246 to have. The connection with the energy source 251 can without a separate RF element RE directly to the hub H3 and thus to the top 12 to lead.

There are now other versions that are more of the structure in 2 differ, and 4 shows a flexible electrode containing a cooled tip as disclosed above. That is, the electrode 62 is elongated and isolated over most of its length. The electrode 62 could be in the form of a catheter made of plastic, a spirally wound or braided structure, or various other tubular forms of insulating and non-insulating material.

In essence, the electrode has 62 a flexible, hollow, externally insulated structure, which at its distal end is in a point 63 ends with a conductive surface. Using techniques known in the art, the electrode can 62 Control elements included to achieve different curvatures. In this case, the curvature of the electrode 62 (as well as the top 63 ) on a hub 66 be controlled by an operating device 67 is used, which can be performed variously as a lever or knob. That is, the previous method according to the operating device 67 with mechanisms in the electrode 62 , such as push-pull wires connected to adjust the degree of curvature, the direction of curvature or the position. Such mechanisms are, as indicated, known and are used in the field of cardiac electrode physiology and endoscopy for target search throughout the body.

The electrode 62 further includes electrical baffles and fluid flow devices mounted internally, as described above with reference to FIG 1 and 2 is described. Accordingly, RF energy from an energy source 64 supplied to generate Ablationswärme, as described above. Furthermore, leads, as described above, lines 68 a stream of fluid coolant from a source 70 to. As with the structures described above, the coolant becomes the tip 63 passed to cool the top.

The structure in 4 can be used especially in ablation of the heart. In general, cardiac ablation catheters are known, but the improved form of the present invention offers expanded capabilities. These forms of flexible electrodes, as described with reference to 4 also include electrodes with a lateral outlet, such as the cervical type, but with chilled tips as described herein.

5 Figure 4 shows an embodiment of the present invention including a satellite temperature monitoring electrode used to monitor the size of a lesion, particularly with respect to the volume or distance from the lesion marker tip. A main electrode shaft 92 is constructed approximately as in the embodiments already described. That is, a hollow electrode 94 carries an insulating coating 96 and has an exposed tip 93 as has already been revealed, and resembles the structure in 1 and 2 also with regard to heating and cooling. However, an extension tip extends 94 from the distal end of the electrode tip 93 and she can have a heat sensor at her end 98 or in the vicinity of which has a similar structure as the sensor 23 , as well as an associated connection line 24 (eg a cable), as shown in 2 is shown. Accordingly, the front end of the shaft 92 ( 5 ) by an exposed length L of the electrode tip 93 completed, and the extension 94 Ablation heating may be at a distance from the tip 93 capture, so that the ablation is further controlled. Therefore, the shaft is the same 92 who has the electrode tip 93 (together with the internal cooling and heating elements), generally the cannula C ( 2 ). The distance around which the shaft protrudes may be determined by the operator with structures similar to those in 2A to set, change or adjust the value of exposure of the tip. stem extension 94 may have similar structures as in 2 and may also include heating and cooling elements.

Similar to the ones already described Versions will be the electrode shaft 92 in 5 at a hub 100 attached via a pair of clutches 102 Connection to a controller unit 104 and a computer support system 106 manufactures. Forms of computer control and display structures will be described in detail with reference to later embodiments.

From the controller unit 104 extends a cable 108 to a secondary hub 110 that is a secondary probe 112 carries the auxiliary heat detection (or heating or cooling) at a position near the top 116 allows for a distance D to the electrode tip 93 is offset. In summary, that shaft 92 represents a controlled heating structure and offers the possibility of the temperature over the length of the extension 98 to monitor. The secondary probe 112 is about a fixed distance D (see line 114 that has a mechanical connection or an insertion distance of the shaft 92 and 112 in relation to the arrangement in the tissue). Accordingly, control by the control unit 104 in combination with the computer 106 based on measurements of temperature, power, voltage, current and / or other lesion parameters (as well as cooling). In this case, as shown, display devices 114 through the control unit 104 which may contain graphic images and gauges.

To support the control, the probe can 112 be coated with insulating material to control the flow of electricity from the top 93 essentially not disturbing. The probe has a sensor 116 at its tip, which indicates the temperature in the tissue, as indicated generally by the arrow 118 is indicated.

When heated by the structure in 5 creates an isotherm or a constant temperature range, as indicated by a broken line 120 which is a surface of constant temperature in the tissue. Again, by keeping the temperatures in different places (such as at the tips 116 . 98 and 93 ), a quantitative indication of the size of the lesion can be determined. Such information may be displayed, monitored and / or controlled (such as by controllers 104 and computer 106 ), and, as indicated, automatic control can be implemented.

6 FIG. 10 shows another embodiment of the present invention including surface mounted electrodes. FIG. Such structures are suitable for ablation in certain organs. For example, a body area 130 represented containing a tumor to be destroyed. The active electrode system 131 contains, as shown, a planar ablation electrode or an ablation applicator 132 that with the body area 130 is shown in contact. The electrode 132 has the form of a plate-like structure, which consists of wire mesh. Alternatively, the electrode 132 take the form of a balloon or bag-like structure containing an electrically conductive mesh, wire or surface material for good RF contact with the body region 130 to enable.

The ablation electrode 132 is via an RF cable 134 with an energy source 136 coupled. As alternatives to this, the source 136 have the form of a microwave, laser, ultrasonic or other DC or AC power source, and therefore they are connected 134 to a facility that source that energy 136 conducts, allowing ablation energy from the electrode 132 on the body section 130 is exercised. The electrode 132 is how in 6 illustrated, further with a coolant source 138 coupled, which may take any of the forms shown here, to the electrode 132 via channels 140 and 142 To supply coolant.

For example, it is believed that there is a desire to have a lesion volume of isotherms in the tissue region 130 as with the broken line drawn circle 144 is indicated. Here is a temperature measurement satellite sensor 146 shown so that he is in the circle 144 extends into it. The sensor 146 is, as shown, via a cable 148 electrically with the source 136 coupled. Accordingly, a spike is generated 170 of the sensor 146 corresponding temperature indications for the source 136 to conduct electrical energy to the electrode 132 as well as the flow of coolant from the source 138 to control.

To complete the electrical pathway for ablation energy is a reference electrode 152 in the form of a flat plate present with another surface of the body area 130 comes into contact. The reference electrode 152 is through a cable 154 electrically with the energy source 136 connected. Accordingly, a circuit from the ablation electrode 132 over the body section 130 to the reference electrode 152 closed. Therefore, the generated flow of electric current heats the tissue and causes a lesion, as explained above. Again the temperature of the electrode becomes 132 because it is cooled, it is limited, and therefore, as explained above, the tissue just below remains relatively cool, and the lesion heat becomes substantially a distance from the electrode 132 "Expelled" and acts in the volume of the circle 144 , From the above, it should be apparent that electrodes having a plurality of Coolants, elements and structures can be used. That is, the disclosed embodiments are exemplary, but other means for cooling an electrode tip are possible. For example, thermoelectric cooling can be utilized by the Seebeck effect whereby a solid state assembly in the tip of the electrode can be powered by electrical current and voltage from external devices, and this in turn can cause cooling of the drug in the tip. It is conceivable that cryogenic substances, such as liquid nitrogen, flow inside the electrode. A combination of cryogenic, freezing and HF heating can be considered as a dual effect of changing the heat distribution near the top of the cooler. Cooled gas can be injected into the electrode and heat, as explained above, can be dissipated by forced convection.

It It should be noted that the cooling fluid, as shown in the examples above, for example through holes in the tip of an electrode in the tissue or body area near emanate from the top can. For example, if the tip is in blood, cerebrospinal fluid or another body or surgical fluid, the cooling fluid could be in these external Be injected area and not via the electrodes to the source or returned to the controller, as is the case with the above examples. If for example, the electrode is in a surgical wound, then could chilled Saline through the holes near be discharged to the top and so cool the top and flush the surgical area. The cooled Saline could through other tubes, Suction elements or channels, which are not directly part of the electrode or the heating structure, of the heating point be sucked off.

The following is with reference to 7 another embodiment (again not to scale) shown, this time in a form for treating a body area 156 a patient, in particular for ablation of a volume, with a broken line 158 is marked. The system in 7 Also contains surface mounted electrodes and contains a coolant source 160 that is both an electrode structure 162 as well as a surface mounted reference electrode 164 Adds coolant. Furthermore, electrical energy from an electrical energy source 166 fed. That means, energy gets through a cable 168 to a hub 170 conducted electrically with the electrode structure 162 connected is. In this case contains the electrode structure 162 a balloon top 172 (shown inflated), as known in the art, which may be found in the section 156 of body tissue. The surface of the top 172 is conductive and guides the tissue in the case of an RF energy source 166 electrical energy too.

The hub 170 further includes fluid lines including a channel 174 , the balloon top 172 Coolant feeds, returns from the fluid and exits the hub, as at a port 176 indicated and explained above, the current corresponding to an arrow 178 takes place.

The power source 166 is also via a cable 180 connected, the electrical contact with the reference electrode structure 164 manufactures. Accordingly, in de electrode structures 164 and 162 according to the systems described above on coolant. Another cooling element 173 is included to modify the overall heat distribution. This element 173 can connect to the power source 166 or not, and serve to provide or not provide heating energy and merely to form a thermal limit to control the extent or shape of the ablation volume. connections 175 and 177 take in or release coolant. Furthermore, further thermal boundary conditions in the body portion 130 be generated.

When operating the system in 7 becomes the ablation electrode structure 162 electrical energy supplied in the volume of the broken line 158 exit to effect the desired ablation. Tissue near the electrode 164 is cooled and not subjected to the heating process. For example, when an RF ablation electrode is inserted into the prostate to treat a carcinoma tumor, an inflatable cooled balloon, such as a balloon tip, may be used 172 , are inserted by introducing it into the rectum near the rectal wall near the prostate, and a cooled reference electrode 164 can be used in the ureter. Alternatively, a cooled RF electrode can be inserted into the ureter to maintain the integrity of the tissue walls of the ureter and rectum, with percutaneous or open electrode insertion into the prostate ablated prostate.

Another potential use of a cooling reference electrode is in use near, in conjunction with or in combination with a secondary ablation electrode, and could be used in the thermal ablation of tumors in the liver using a cooling electrode in one of the large vessels supplying the liver with an RF electrode inserted into the tissue of the liver. So can the Heating process can be performed by the RF electrode, and the cooling process or thermal boundary conditions can be implemented by the cooling electrode.

A similar situation may exist in the pancreas, with a resizable RF ablation electrode, such as the electrode structure 162 , can be used in the pancreatic duct and can be extended to the tissue of the pancreas and the duct wall. Thus, RF heating can expel the heat into the pancreas where a tumor or other anomaly may be present. At the same time, the electrode may have cooling circulation, so that the tissue immediately adjacent to the electrode in the passage wall can be kept sufficiently cool so that it is not destroyed. A ring of annular lesions made by RF heating can be generated in this way, with an inner circle not heated and destroyed, while smaller circles thermal to a larger radius from the electrode or balloon or stent electrode can be destroyed.

It is possible, too, that big cooled RF ablation electrodes, Microwave electrodes or laser ablation systems on the tissue the surface of the body or a tissue inside the body, as in open surgical areas or in body cavities, vessels arranged or be brought into contact with it, with other reference or neutral electrodes that are cooled or not cooled are, near or be arranged in a certain orientation relative to them can.

Of Further, accordingly, a variety of RF electrodes, as explained above, are used, which are either electrically activated or inactive are so specific thermal and electrical boundary conditions in tissue and thus tissue areas no heat ablation undergo at the same time other areas of tissue, the from the configuration electrode and thermocouples as well as the operator be controlled, destroyed become.

One Computer system can, as indicated above, used effectively be used to calculate the thermal and electrical distribution and a desired one heat distribution to reach in the tissue. This heat, convection and conductivity properties of tissue and fluids, as well as Maxwell's equations, to account for density and to determine the distribution of the tissue, all this with a Computer workstation and with a corresponding graphical display takes place.

Of Furthermore, as far as graphic displays are concerned, it makes sense accordingly be, real-time or interactive images of CT, MRI, PET, etc. in Reference to the time course and the spatial distributions of heat ablation to monitor. Control devices, such as computers, can the process of this warming predict and control. CT and MRI imaging is for thermal effects and tissue changes, those with HF heating are connected, sensitive, and these can be during or immediately after monitored the heating process become. For example, tissue necrosis, edema breakdown of the blood / brain barrier etc. and visible immediately or very soon after heat ablation. such Apparitions can can be used to monitor and feedback the ablation size and the heating process to control. Such changes can monitored and monitored using computer graphics techniques become.

In the following, embodiments of the system are considered that are implemented with computerized control and also provide graphical displays with real-time components. Such an embodiment is in 8th and will be described below. In essence, parameters of the situation are reduced to representative signals that are processed to provide displays. Computed data showing an electrode in a tissue environment can be combined with sampled image data (stored, for example) to provide a variety of composite displays.

8th shows an ablation electrode structure 260 (right), which may have any of several shapes including the above-described embodiments. The electrode structure 260 is powered by an RF generator 262 fed and cooled with coolant coming from a source 264 is supplied. A tax system 266 (left) regulates various parameters (energy and coolant flows) according to a given plan, which is used in a computer system 268 (bottom center). It should be noted that various forms of feedback control systems are known and for implementation in the system 268 are sufficient. The literature on feedback control systems is well known, as exemplified in the book MODERN CONTROL ENGINEERING by K. Ogata, Prentice-Hall, Englewood Cliffs, New Jersey, 1970.

In operation, the computer system receives 268 Parameters via a bus 267 from the control system 266 in order to carry out its own control and implement the desired program. That is, the computer system 268 imple mentions a monitoring and feedback program relating to the parameters associated with the function of the ablation structure 260 related. Such functions are over the bus 267 implemented with known data processing and control methods.

K

die Wärmeleitfähigkeit des Gewebes ist,

σ

die elektrische Leitfähigkeit des Gewebes, ist,

T

die Temperatur in dem Gewebe ist, und

dQ_c/dt

die Rate des Wärmeverlustes aufgrund von Blutzirkulation ist (entnommen aus der obenstehenden Bezugsquelle von Cosman et al.).

A simple two-parameter control system can work with the control system 266 together with the computer 268 and input data (units 272 and 274 ), which include a heat distribution calculation by the computer 268 heard, as shown. A look-up table or function generator defines the ablation volume, ie, length and width dimensions, as a function of the shape of the tip and the temperature of the tip. The temperature T ₀ of the tip could be clamped by cooling fluid to a fixed value, or if no cooling is performed, the value T is ₀ measured by thermal sensors. Using tables as described, for example, in the publication by Cosman, et al., Entitled "Theoretical Aspects of Radiofrequency Lesions in the Dorsal Root Entry Zone," Neurosurgery 15: 945-950, 1984, the width or the minor diameter of the elongated revolution ellipsoid representing the ablation isotherm and corresponding to a particular energy output level from the lesion generator at a particular tip temperature near the electrode, which could be either empirically experimental Derived from the equilibrium equation, where:

K

the thermal conductivity of the tissue is

σ

the electrical conductivity of the tissue is,

T

the temperature in the tissue is, and

dQ _c / dt

the rate of heat loss due to blood circulation is (taken from the above reference of Cosman et al.).

Therefore, the surface of revolution corresponding to the ablation temperature of approximately 50 ° C could be determined as a functional equation S (T ₀ , R ₀ , L ₀ , P ₀ , x, Y, z) = o

This could be the equation of a surface containing the X, Y, Z coordinates with respect to the tip of the electrode as a function of the tip radius parameter R ₀ , the peak length L _0, the tip temperature T _0, and the energy P indicates the RF lesion generator. This area S could be displayed in the coordinate system of the electrode or in the three-dimensional coordinate system of the CT or MR data or in a stereotactic coordinate system related to a localization structure or localization markers or an external device (arc, frame, etc.) in the vicinity of the patient , The surface would then be displayed on the computer as a red spheroid around the tip. Their relationship to the defined lesion volume could be visualized by graphing, as is done, for example, for radiosurgery in the XKnife product of Radionics, Inc. (Burlington, Massachusetts).

A simple special illustrative program for implementation by the computer system 268 is in 9 shown. It essentially represents an initialization process of setting parameters as indicated (Block 361 ). That is, ablation time, energy, electrode temperature, and allowable impedance are fully initialized. Thereafter, the process is started with the parameters set, as with the block 363 is indicated. From this stage, the data is monitored. That is, the temperature is measured as indicated in the various embodiments disclosed. If a temperature above 100 ° C is measured, as in the query block 365 implied, the procedure is terminated (block 367 ).

If the temperatures are below the critical value, next the maximum allowable impedance is of interest. That is, when the temperature is exceeded, as with the query block 369 shown, the RF energy decreases, as in block 371 you can see. It should be noted that the temperature, as indicated, is checked regularly in the program. That is, the system may perform a continuous monitoring of the temperature with a program intervention to terminate the process at any time when too high values are detected. For illustrative purposes, however, the program will be described in a step-by-step process.

When acceptable values of temperature and impedance have been set (blocks 365 and 369 ), the energy is measured in relation to the desired value (block 373 ). Too high a value in turn leads to a reduction in energy (block 371 ), otherwise the energy will increase if it is too low (block 375 ). So the energy is regulated to reach the desired value.

When the desired value of energy is set, as with the block 377 indicated, the temperature of the tip measured. Too high a value of the temperature of the tip triggers an increase in the flow of coolant (block 379 ) and an examination of the other parameters, as indicated in 9 is indicated. Otherwise, the final Ab ask how with a block 377 shown whether the desired Ablationsvolumen has been achieved. If this is the case, the process is terminated (block 383 ), and otherwise, as with the line 385 indicated, the process cyclically continued, ie the block 365 returned.

The system receives to be used for computer-related presentation in 8th also data from other sources, ie a sample data unit 272 , a sound data unit 274 and a remote temperature unit 276 using ablation and distribution software 267A work. Accordingly, the computer system 268 in addition to implementing a basic ablation control program, unprocessed display data for a graphics display driver 277 (Imager) for operating a display unit 278 ready. So there are several ads on one screen 279 Slices, timings, scale changes and digital subtractive representations, as well as digital and analogue measurement representations are available. Exemplary forms of advertisements are in 10 and are discussed below.

As for the data sources, the sample data unit stores 272 two or three dimensional graphical data relating to the target of the surgical procedure, which are selectively provided so that the body region can be visualized before, during and after the procedure for the surgeon. The through the scanning unit 272 stored data may take the form of CT or MRI data generated prior to surgery, as is known. The data may be either stereotactic or non-stereotactic, include fixators, fiducials, graphical reference devices, etc. Forms of such data and their processing are disclosed in U.S. Patent 4,608,977 to Brown entitled "System Using Computed Tomography As For Selective Body Treatment" (September 2, 1968) The Radionics, Inc. (Burlington, Massachusetts) Literature is also relevant.

The sonic / ultrasonic unit 274 may be of a form known in the art for generating sound data, such as from a stethoscope, an electronic microscope, a sound detector, to visualize tissue. For example, the data is provided and processed to the electrode structure 260 with respect to the body section. It can by the sound data (unit 274 ) and the sampling data (unit 272 ) represented by the computer system 268 combined to provide display signals for composite displays.

It can various other messages will be available to inform and to direct the intervention, with regard to the flows of energy and coolant is controlled. The program can be implemented in this way that there are computational algorithms, lookup tables, heuristic algorithms, clinical Historical data, mathematical calculations, field and heat distribution calculations Finite Element Methods lock in, solutions analytical form, computer-theory-method, of any or all of which can be used to pre-plan and image data as well as functional processes to steer differently.

10 represents exemplary displays used in the operation of execution in 10 on the screen 279 can appear. An ad 10A represents a real-time or pre-planned path of a probe path 282 This represents the path of an electrode tip into the body, ie a tumor structure, as with a cloud of points 284 is shown, indicates. It should be noted that CT contrast agents can be used to "see" the ablation volume during or after thermosurgery, with the result that the display produces a direct view of the results immediately after the heating process.

Another screen 10B represents a pre-planned electrode path 290 in a disk 291 in three-dimensional view dar. Of course, the disc 291 based on sampled or scanned data, that of the unit 272 ( 8th ) to be provided. The indication of the electrode shape (ie tip length and diameter as well as shape) can also be made as a three-dimensional or stereotactic view with respect to other body parts.

Another displayed screen 10C shows a playback 298 a slice of the patient's body, taking a path 300 is shown for a thermosurgical probe. Several electrode paths can be shown, which are either parallel or non-parallel, stereotactic and located at various locations in the body.

In a message 10D is a timed or preplanned chart line 312 for example, which indicates the thermal sensor reading of temperature sensors associated with the coolant fluid electrode tip, additional probes or cooling or heating devices, and data from multiple sensors, etc., as previously described. A digital display, mark, or multiple digital displays can be displayed in a pane 314 to be shown. Accordingly, different graphic For example, a curve may represent tissue temperature, while a green curve represents fluid temperature and a yellow curve represents fluid temperature at another location. In such a format, an orange curve may represent the tissue temperature as measured by a satellite electrode.

At a display 10E shows a diagram line 318 the output of the RF generator as a function of time. At the same time presents a pane 320 a digital or analog representation, current energy, current, voltage, or other energy output or monitored ablation parameters.

In a message 10F represents a curve 326 In general, an impedance drop is expected when tissue is heated, with an increase in impedance as approaching or reaching charred or boiling tissue occurs in this connection, to a publication by ER Cosman, et al. titled "'Radiofrequency Lesion Generation And Is Effects on Tissue Impedance,' Applied Neurophysiology, 51: 230-242, 1988, is to refer. The system could control or display the extent of the ablation volume and protect it from overcooking and uncontrolled gas formation.

In 11 is a combined embodiment in terms of body tissue shown as having the 1106A . 1101 and 1106B marked areas is shown. Natural openings or channels in the body are with 1106 and 1115 shown. These channels may be external openings, ie, rectum, urethra, throat, bronchi, etc.), or internal channels (ie, blood vessels or ducts such as the aorta, arterial or venous vessels, ducts or vessels of the liver, pancreas, etc.). , Aqueducts of the liver, pancreas, kidney or other organs, ventricular aqueducts in the brain, intestines, throat, bronchi, etc.). Electrode catheter 1109 is located in channel 1106 , and the inflatable electrode 1117 has an area on the wall 1115A so that it is in electrical and / or thermal contact with it.

Applicator electrode 1116 can be inflatable, such as a balloon or condom, and can be isolated over much of its surface, and internal coolant circulation takes place through internal channels (such as 1135 ) instead of. The electrode 1103 for penetration into tissue is located in the tissue area 1101 so that their electrode tip 1104 is located at a target volume that with line 1102 is shown. The electrodes may be structures such as those already described and corresponding heat sources (such as 1127 . 1124 and 1120 which may be interconnected or separate) and cooling sources (such as 1128 . 1129 and 1119 ) as they are described. The energy sources 1127 . 1124 and 1120 can be RF sources and they can be so for example through lines 1140 . 1150 and 1141 be connected and at different poles and different temporal phase relationships (such as sequential or graduated arrangements) between the electrode tips 1109 . 1121 and 1117 to produce different heating effects at different times and at different locations. Each electrode may be a cooling source (such as 1128 . 1122 and 1119 ) or not, which can be controlled with each other, and also heating controls (as with broken lines 1041 . 1150 and 1140 shown), and these can all be controlled by a computer ( 1124 ), this being exemplified below. By using appropriate cooling and electromagnetic boundary conditions between one or more of the electrodes, the ablation zone (dashed line 1121 ) the target volume (ie, a tumor, such as line 1102 ) enclose and delicate tissues in channels 1106 and 1115 Do not destroy as they are kept cool. One, all or more of these electrodes may be used depending on the clinical case.

A field of application is the prostate. The electrode 1109 Can be a cooled catheter electrode (if necessary, also steerable) in the urethra 1106 be and 1116 can be a cooled probe in the rectum 1115 be. The electrode 1104 can pierce the rectal wall into the prostate, where a tumor ( 1102 ) has been visualized by imaging. Suitable electrode cooling creates an ablation zone (with 1102 shown) that the prostate tumor (ie line 1102 ) encloses, however, sensitive mucous membranes on wall 1115A of the rectum and urethra (as with 1106 shown) or seminal vesicles (not shown) not destroyed. Imaging at the same time as ablation or thereafter can check or control the extent of ablation.

Another area of use is the liver, the pancreas or the kidney (tissue 1101 can represent these organs). Electrode catheter 1108 is inserted percutaneously via a vessel (ie in the groin) or directly over the abdomen when the electrode is in place 1 is shown, is designed so that the electrode tip 1109 in a liver or pancreatic vessel and / or a gangway. A second electrode 1103 can be introduced so that their tip 1104 in tumor 1102 lies. cooling tip 1109 protects the vessel or the gland, while tumor 1102 is removed. In these examples, electrode 1116 also be actively heated with radio frequency, and it may be like a balloon, a condom, inflatable or stretchable, or a stent (a flexible wire mesh structure widely used in medical practice and marketed, for example, by Cook, Inc.) to the channel 11 fill in and stick to the walls (ie area 1115A ) and to get in touch with them. Part of their area 1117 Heat may "bump" into the tumor and may also be cooled to prevent damage to the gait so that the gait can continue to process normal biological material.

11 can also represent the situation in which the channel 1115 the colon is and the electrode 1116 is inflated to press against the colon wall, and by cooling and RF heating, the ablation of a tumor (ie, volume 1102 ) in or near the colon wall without completely destroying the colon wall itself.

For the expert is obvious that the system with the variety of modifications can take many forms. In summary, however, it should be noted that different energy sources are used as an alternative to RF energy can be. The energy could for example, in the form of microwave energy, an ultrasonic heater, directs the sound waves into the tissue, or a direct source of energy. The heating could, as also indicated by various forms of structures or with different openings provided structures are executed.

alternative Electrodes can the form of cannulas with fiber optic channels have to send laser light into the tissue and heat in one To create depth. Different geometries (curved or straight) of laser systems can be used become. One form of RF energy source may be the RFG-3C Lesion Generator However, others could be made as manufactured by Radionics, Inc. Electric energy sources, such as electrosurgical RF energy sources, bipolar cautery sources etc. are used.

As also indicated in disclosed embodiments, can along with the cooling system, like Accordingly, various graphic displays are disclosed to get integrated. Different controls can be used, for example, for the cooling system and the heating system coordinating through supervised phenomena which can be displayed.

As With reference to the disclosed embodiments, there are numerous modifications of electrodes or body terminals executable, too which tubular shafts, square shaft etc. belong. Plane electrodes, surface electrodes, Multiple electrodes, arrangements of electrodes, electrodes with lateral Outlet or laterally exiting openings, electrodes with balloon tips, Stretchy tips or compliant tips can be used within the system be considered. Electrodes with steerable tips and Electrode shank that can be adapted or molded or which are deformable, can be considered within the system. Electrodes that so executed are that they are in the body tissue or on the surface of the body or in cavities in the body can be arranged can be developed and are hereby included. Electrodes can be temperature sensors inside or in their vicinity or not, and the ablation process may be, for example accomplished be by adding heat energy supplied and the applicator is cooled is monitored without the temperature or controlled, but only using empirical Parameters, such as heating energy and temperature / current of the cooling fluid. Given these considerations should implement and systems, as well as for the expert at hand in the wider sense and with reference to the following claims to be viewed as.

Claims (15)

A thermal system for ablating tissue of the body of a patient, comprising: a terminal structure including: a hollow electrode ( 11 ) for approaching the tissue and for delivering ablation energy to the tissue and an energy source ( 16 ), which with the hollow electrode ( 11 ) is coupled to heat the tissue; a cooling system coupled to the termination structure for supplying coolant adjacent to the tissue and having a fluid flow channel (12); 26 ) for supplying the coolant adjacent to the tissue and containing a fluid source (FS); a temperature sensor ( 23 ), which senses temperature adjacent to the tissue; at least one reference electrode (R); and a microprocessor ( 44 ) connected to the energy source ( 16 ), with a temperature monitoring device ( 20 ) and coupled to the fluid source (FS) to receive data on flow rates and temperatures and to perform control, the temperature monitor (15) 20 ) through pipes ( 22 . 24 ) electrically with the temperature sensor ( 23 ), characterized in that: the electrode has an elongate hollow discharge electrode ( 11 ), which at a distal end with a ge closed conductive tip ( 12 ) and concluded by the closed executive 12 ) is electrically non-conductive, wherein the fluid flow channel ( 26 ) at least the closed conductive tip ( 12 ) of the electrode ( 11 ) Supplies coolant. System according to claim 1, characterized in that the energy source ( 16 ) an RF energy supply ( 16 ). System according to claim 1 or 2, characterized in that the electrode ( 11 ) is made of a conductive material, the closed conductive tip ( 12 ) having. System according to claim 1, 2 or 3, characterized in that the closed conductive tip ( 12 ) is formed as a tapered structure. System according to one of the preceding claims, characterized in that the electrode ( 11 ) comprises a cannula (C) having an elongated shaft which is in the closed conductive tip ( 12 ) and disposed adjacent to the tissue. System according to one of the preceding claims, characterized in that the temperature monitoring device ( 20 ) the temperature near the closed conductive tip ( 12 ) of the electrode. A system according to any one of the preceding claims, further comprising: a guide rod (SS) having an elongate body and a tissue piercing distal end (Fig. 186 ); and an open electrically insulating sheath (CS) adapted to removably receive the guide rod (SS). System according to claim 7, wherein the electrode ( 11 ) is adapted to telescopically engage the insulating sheath (CS) upon removal of the guide rod (SS) from the insulating sheath (CS) to selectively define a portion (L) of the conductive surface of the electrode (CS). 11 ) and to form at least one electrical current flow section and to generate primary electrical current flow through tissue to be penetrated and to form a lesion of predetermined size. A system according to any one of the preceding claims, wherein the conduit is an inlet tube ( 241 ) axially in the hollow electrode ( 11 ) and has a distal end that is close to the closed conductive tip (FIG. 12 ) of the electrode ( 11 ), and an outlet tube ( 246 ), which forms a fluid outlet path, wherein, when the electrode ( 11 ) Heat generating electrical current flow through adjacent body tissue causes the inlet tube ( 241 ) Fluid into the internal cavity of the electrode ( 11 ) and the outlet tube ( 246 ) Fluid from the internal cavity of the electrode ( 11 ) to dissipate excess heat from the electrically conductive portions of the electrode and to maximize the formation of the lesion. System according to claim 1, characterized in that the system further comprises a planar electrode ( 132 ) having a planar conductive surface for contact with a body portion ( 130 ). System according to claim 10, characterized in that the planar removal electrode ( 132 ) with the coolant source ( 138 ) is coupled. System according to claim 10 or 11, characterized in that the planar removal electrode ( 132 ) has the form of a plate-like arrangement consisting of a metal mesh. System according to claim 10 or 11, characterized in that the planar removal electrode ( 132 ) is a bag-like structure containing an electrically conductive mesh. System according to one of the preceding claims, characterized characterized in that the fluid source (FS) the tissue to the end structure adjacent to a temperature below 100 ° C holds. System according to one of the preceding claims, characterized characterized in that the fluid source (FS) the tissue to the end structure adjacent to a temperature below 37 ° C holds.